This invention relates generally to the providing or supplying of inflation gas and, more particularly, to the providing or supplying of such inflation gas via an inflation assembly with extended filling capability such as may be desired for certain inflatable passive restraint systems for use in vehicles for restraining the movement of an occupant in the event of a vehicular collision.
It is well known to protect a vehicle occupant by means of safety restraint systems, i.e., “passive restraint systems”, which self-actuate from an undeployed to a deployed state without the need for intervention by the operator. Such systems commonly contain or include an inflatable vehicle occupant restraint or element, such as in the form of a cushion or bag, commonly referred to as an “airbag cushion.” In practice, such airbag cushions are typically designed to inflate or expand with gas when the vehicle encounters a sudden deceleration, such as in the event of a collision. Such airbag cushions may desirably deploy into one or more locations within the vehicle between the occupant and certain parts of the vehicle interior, such as the doors, steering wheel, instrument panel or the like, to prevent or avoid having the occupant forcibly strike such parts of the vehicle interior.
Various types or forms of such passive restraint assemblies have been developed or tailored to provide desired vehicle occupant protection such as based on either or both the position or placement of the occupant within the vehicle and the direction or nature of the vehicle collision, for example. In particular, driver side and passenger side inflatable restraint installations have found wide usage for providing protection to drivers and front seat passengers, respectively, in the event of head-on types of vehicular collisions. Driver side and passenger side inflatable restraint installations do not, however, generally provide as great as may be desired protection against vehicular impacts inflicted or imposed from directions other than head-on, i.e., “side impacts.” In view thereof, substantial efforts have been directed to developing inflatable restraint installations having particular effectiveness in the event of a side impact.
Upon deployment, the time period during which an airbag cushion remains pressurized is commonly referred to as “stand-up time.” In practice, driver side and passenger side airbag cushions are typically desirably designed to begin deflating almost instantaneously upon deployment such as to avoid presenting an undesirably hard or ungiving surface to an oppositely situated vehicle occupant. However, airbag cushions that provide substantially longer stand-up times may be required or desired in the event of certain accidents or collisions in order to provide a suitable desired level of occupant protection. For example, one particularly troublesome form of side impact is commonly referred to as a “roll-over.” In a roll-over incident, a vehicle may undergo a partial, complete or multiple roll-over. As will be appreciated by those skilled in the art, roll-over accidents can be particularly demanding on inflatable restraint systems. In particular, an airbag cushion designed to provide occupant protection in the event of a vehicle roll-over may be required or desired to remain pressurized for an extended or prolonged period of time, as compared to usual or typical driver side and passenger side airbag installations. For example, a roll-over protection side impact airbag cushion desirably remains pressurized or provides a stand-up time as long as about 5 seconds.
One particularly effective form of side impact inflatable restraint is the subject of HÅland et al., U.S. Pat. No. 5,788,270, issued 4 Aug. 1998, the disclosure of which patent is hereby incorporated by reference herein in its entirety and made a part hereof. Inflatable elements, such as disclosed in HÅland et al., U.S. Pat. No. 5,788,270, may desirably include an inflatable portion formed from two layers of fabric with the front layer and the back layer of the fabric woven together at selected points. In particular embodiments, such selected points are arranged in vertically extending columns and serve to divide the inflatable part into a plurality of vertical parallel chambers. The spaces between the selected points permit internal venting between adjacent chambers of the inflatable element. Particular such inflatable devices/elements, such as utilized in applications to provide protection over an extended area and having a generally planar form, are frequently referred to as “inflatable curtains.”
A one piece woven construction has been found to be a particularly effective method of forming such inflatable element airbag cushions. In particular, one piece woven constructions have been found to provide a relatively low cost method of constructing suitable such airbag cushions which provide desired stand-up times. While inflatable element airbag cushions can, as is known in the art, be fabricated of various materials, nylon 6,6 has been found to be a particularly effective and useful material for use in the making or manufacture of inflatable curtain elements such as described above and having a one piece woven design.
In addition to an airbag cushion, inflatable passive restraint system installations also typically include a gas generator, also commonly referred to as an “inflator.” Upon actuation, such an inflator device desirably serves to provide an inflation fluid, typically in the form of a gas, used to inflate an associated airbag cushion. Many types or forms of inflator devices have been disclosed in the art for use in inflating an inflatable restraint system airbag cushion.
One common type or form of inflator device utilizes or relies on a stored compressed gas. Upon actuation, such devices release the stored gas into an associated airbag cushion to effect the inflation thereof. Such inflator devices are sometimes referred to as cold gas inflators as in such inflators the gas typically undergoes either no heating or only minor, insignificant heating, e.g., heating which is less than the cooling that occurs due to expansion as the gas is released from the inflator.
In the past, rollover applications typically have required the use of such cold gas inflators. In particular, the gas discharged or provided by such inflator devices typically expands and warms upon release, such that the cold gas inflator is able to maintain pressure in a sealed airbag for relatively long periods of time. Unfortunately, cold gas inflators typically are much larger and heavier than desired.
Another common form or type of inflator device used in inflatable passive restraint systems is commonly referred to as a pyrotechnic inflator. While various combustible pyrotechnic materials are available, such inflator devices typically produce or result in a relatively high temperature product gas, derived from the combustion of a pyrotechnic gas generating material. In practice and such as due to the effects of heat, such pyrotechnic or hot gas-providing inflators can typically be made smaller and lighter and use fewer moles of gas as compared to a cold gas inflator in order to provide the same volume of gas.
In addition, the gas generated by the combustion of such pyrotechnic materials may contain variously sized particulate material. Thus, it is relatively common to include within such inflator devices a filter or other selected gas treatment component or element such as effective to perform various functions or treatments, such as, provide for one or more of cooling, flow redirection and filtering (e.g., particulate removal) of or by a contacting stream, such as generated gas, for example. Nevertheless, gas discharge temperatures in the range of about 1300 K are common for conventional pyrotechnic inflator devices.
However, pyrotechnic or other forms of hot gas-providing inflators normally do not generally provide or result in extended stand-up times of associated inflatable elements, such as required or desired for particular restraint installations, as described above. More particularly, as the hot (e.g., elevated temperature) gas produced or provided by such inflator devices rapidly cools, the pressure within the associated airbag cushion rapidly diminishes such that the stand-up time of such associated airbag cushion is limited or reduced.
Moreover, it is common to include within an associated airbag cushion a heat resistant coating or one or more strategically placed patches of heat resistant material such as to minimize or avoid direct contact of the hot inflator discharge onto unprotected airbag cushion material. Unfortunately, the inclusion of a heat resistant coating or patches of heat resistant material within such inflatable cushion elements is not always practical. For example, such inclusion almost invariably results in the side impact cushion, when folded such as in a stored condition, being more bulky than is generally desired.
In addition, the gas treatment component or element of such pyrotechnic, hot gas-providing inflators may retain significant amounts of heat. Consequently, care must be taken that such heat not undesirably “soak out” over time in a manner such as may damage objects in contact or proximity therewith.
As will be appreciated, inflatable curtain restraint devices can be particularly demanding of an associated inflation assembly. For example, inflatable curtain restraint devices are typically required to be deployed in position in less than 20 milliseconds and have an inflatable curtain internal pressure of greater than about 50 to 80 kilopascals at 30 milliseconds following actuation.
In view of the above, there is a need and a demand for inflation assemblies particularly suited for inflation of restraint devices, such as rollover inflatable curtains.
Further, there is a need and a demand for such inflation assemblies that are smaller and lighter in weight than cold gas inflators. In particular, there is a need and a demand for a smaller, lighter inflator that can fill a rollover curtain inflatable element using heated gas, yet maintain an extended stand-up time for such a rollover curtain inflatable element.
Still further, there is a need and a demand for such an inflation assembly that minimizes, reduces or eliminates issues relating to heat “soak out”.